1. Field of the Invention
The invention relates to a gas-cooled electric machine; in this case, fresh gas is sucked in from below, passes into an inlet chamber and is conveyed by means of an axial ventilator into the end-winding cavity of the stator, where it splits up into a plurality of component streams for cooling the stator and rotor.
2. Discussion of Background
In gas-cooled turbogenerators, the cooling is ensured by axial ventilators which are normally mounted on both sides of the rotor on the shaft thereof and deliver the required quantity of cooling gas and a specific pressure head (cf. company publication "Turbogeneratoren fur 18 . . . 230 MVA mit Luftkuhlung WX und WY" ["Turbogenerators of 18 . . . 230 MVA having WX and WY air cooling"], Printed Publication No. CH-KW 160887, in particular the longitudinal section on page 9).
In the known air guides upstream and downstream of the axial ventilator, the prescribed sense of rotation of the rotor generates an inlet spin in the sense of rotation. The approach flow to the axial ventilator takes place as a rule only from one side, for example from below from the coolers arranged under the machine and not--as would be desirable--from all sides. These two circumstances mean that different air speeds prevail at the circumference in the end-winding cavity, as a result of which the cooling effect is uneven. This in turn means poor utilization of the machine.